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Aqua(malonat0-0,O') (1,l O-phenanthroline)copper(ii) crystallizes in the triclinic space group P i with a = 11.560(4), b = 11.734(5), c = 12.491 (2) A, a = 92.1 2(2), p = 105.50(2), y = 109.28(3)", and Z = 2. The structure consists of two independent monomeric [Cu(phen)(mal) ( H 2 0 ) ] molecules with three water molecules in the lattice. The CuN,O,O' chromophore is distorted square pyramidal with a symmetrically co-ordinated phen molecule (mean CU-N 2.01 8 A) and a symmetrically coordinated malonate ion (mean Cu-0 1.91 4 A) in the plane of the square pyramid and a water molecule at 2.266 A. The relatively short Cu-0 distance has been attributed to phen being a stronger n-acid. The compound and its several related complexes show complete loss of water molecules at ca. 100 "C followed b y stepwise degradation of the organic ligands. Thermogravimetric analysis and visible reflectance spectral results are discussed in relation to the k n o w n structure of the title compound.Ternary complexes of the copper(1r) ion containing an a,a'-diimine and an oxygen-donor ligand have been extensively investigated.' Recently it has been reported that the complex containing the 2,2'-bipyridyl (bipy) and the oxalate ion (ox) exists in two forms [Cu(bipy)(ox)(H20)]*2H20 (A) and [Cu(bipy)(ox)]-2H20 (B). X-Ray structural analyses demonstrate that the former consists of a monomeric copper(i1) ternary complex while the latter contains a bridging oxalate ion. In view of the close structural similarities between 1,lO-phenanthroline (phen) and bipy as well as between malonate and oxalate, the ternary complex [Cu(phen)(mal)(H,O)] has now been reexamined through thermogravimetric analysis (t.g.a.1, spectroscopic and structural measurements. As there have been few studies on the thermoanalytical behaviour of these complexes the t.g.a. has been carried out on several related complexes in the present investigation. Such results are useful in understanding the properties and structural characteristics of the complexes in the solid state. ExperimentalPreparation of' Complexes.-The complexes were prepared according to the methods described earlier.'** Crystals of [Cu(phen)(mal)(H20)].1.5H20 were obtained by slow evaporation of a water-methanol (3:2) solution. A blue crystal of approximate dimensions 0.12 x 0.42 x 0.47 mm was sealed in a 0.5-mm glass capillary tube for X-ray data collection.fliysicul Mc.usurements.-The reflectance spectra of the solid complexes were recorded using a Shimadzu UV 240 spectrophotometer and a Perkin-Elmer Lambda 9 u.v.-visible-near i.r. spectrophotometer equipped with a standard reflectance attachment. The i.r. spectra (4 000-200 cm-') obtained from KBr or CsI pellets were recorded with a Perkin-Elmer 599 i Supplementary data acailahle (No. SUP 56604, 5 pp.

IV respectively. Reactions of the respective bidentate ligands I, II, 111 and IV with [Os,(CO),,( MeCN),] gave the novel triosmium clusters [Os,(p-H)-(CO),,(L-L)] 1,2,3 and 4 involving cleavage of one Si-H bond. Similar reactions of ligands II and IV with [Os,(p-H),(CO),,] afforded t w o new clusters [Os,(p-H),(CO),(L-L)]5 and 6 respectively. The structures of 1, 2, 4 and 5 have been determined by single-crystal X-ray diffraction techniques. In each case, the ligand assumes a chelating mode across the long edge of the osmium triangle which is also bridged by a hydride. The high-performance liquid chromatographic behaviour of these clusters has also been determined and correlated with the size and nature of the ligands.

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